The present invention generally relates to methods and apparatuses for dissipating heat away from devices generating heat. In addition, the invention relates to methods and other apparatuses for converting heat energy into other forms of energy.
Since the thermodynamic xe2x80x9cavailability,xe2x80x9d or energy content, of a solid or fluid increases strongly with absolute temperature, efficient electric power generation from a heat source is usually performed at elevated temperatures, often in the range of 600xc2x0 C.-800xc2x0 C. In the categories of high temperature conversion, the systems are generally large, with each generator unit producing megawatts of electric power and occupying a volume of 10 m3 to 100 m3. Alternatively, lower temperature equipment operating between 100xc2x0 C. and 200xc2x0 C., have been developed to recover energy from solar-concentrator heated fluids, geothermal sources and waste heat rejected by high temperature conversion systems.
One prior art approach of utilizing waste heat is taught by U.S. Pat. No. 3,878,410, issued to the United States Energy Research and Development Administration, which is directed to a two-phase liquid metal magneto-hydrodynamic generator. The ""410 patent uses a gas injected into a liquid metal which reduces the density of the liquid metal causing an increased convection flow of the liquid metal within a channel. The liquid metal flows past a heat source where the heat is transferred to the liquid metal. This prior art contains deficiencies, though. For example, as disclosed, the ""410 patent requires a pump to circulate the liquid metal through the channel. This additional pump not only adds components to the system and requires maintenance; but also, consumes electrical power. Thus, the ""410 patent has to pay an electrical energy penalty for the required pumping. Further, a pump adds vibrational and acoustical interference to the system.
In the marketplace, many products generate heat in the low temperature range below 150xc2x0 C. For example, electrical components, such as integrated circuits including a central processor unit (CPU) for a computer operating in close proximity within an enclosed electronic apparatus, produce heat. To prevent thermal failure of one of the electrical components in the enclosed electronic apparatus this heat needs to be dissipated. These enclosed electronic apparatuses are common and typically include personal computers, laptop computers, display monitors, computer peripherals, television sets, projectors, projection monitors, handheld personal digital assistants (PDAs), cellular phones, facsimile machines, video cassette recorders (VCRs), digital versatile disc (DVD) players, audio systems and similar equipment.
Thermal management of the electronic components in the enclosed electronic apparatus is necessary to prevent the enclosed electronic apparatus from failing or to extend the useful life of the enclosed electronic apparatus. For instance, a typical CPU operating in a personal computer may operate at a maximum temperature of 70xc2x0 C. without experiencing a thermal failure; but due to the heat generated by a typical CPU, however, the temperature often reaches 100xc2x0 C. and above which could lead to thermal failure.
The present invention provides a heat dissipating device and method useful for converting heat energy to work energy operating in low temperature ranges and with low temperature differentials.
In an embodiment, the invention provides the heat dissipating device and method for using same in which heat emitted by an electrical component is dissipated and converted to work energy without additional input energy.
In an embodiment, the heat dissipating device includes a shape memory alloy member having a first configuration in the austenite state according to a first temperature. The shape memory alloy member changes phase via hysterisis when exposed to heat above a predetermined temperature wherein the shape memory alloy member thermally contracts to a second configuration corresponding to the martensite state upon cooling to a second temperature resulting in a reciproral displacement of the shape memory alloy.
In an embodiment, the heat dissipating device includes a heat exchanger which is thermally attached to the shape memory alloy member to dissipate the heat from the shape memory alloy member. Further, a bias member which is flexably connected to the shape memory alloy member biases the shape memory alloy member back to the first configuration after the heat is dissipated.
In an embodiment, the invention includes an energy converter to produce current in response to the movement of shape memory alloy member and to extract the current to an electrical storage. This embodiment also provides that the bias member is a spring connected substantially near a first end of the shape memory alloy member while the heat exchanger thermally attaches to a second end of the shape memory alloy member.
In an embodiment, the invention includes a plate member to thermally attach to a plurality of shape memory alloy members. In this embodiment, the bias member connects to the plate member to bias the plate member causing the plurality of shape memory alloy members to extend back to the first configuration.
The present invention also provides for methods of dissipating heat from the electrical component. The method also provides for regenerating electricity from the heat removed from the electrical component.
In one method, at least one shape memory alloy member is disposed within an enclosure wherein a first end is positioned adjacent to an electrical component while a second end is positioned adjacent to a heat exchanger. Within the enclosure, the shape memory alloy member has a first configuration corresponding to a first temperature. The shape memory alloy member is positioned adjacent to the electrical component, in the first configuration.
As the shape memory alloy member is exposed to the electrical component, the heat from the electrical component transfers to the shape memory alloy member. Accordingly, the shape memory alloy member undergoes a phase change by the heat from the electrical component. The shape memory alloy member phase changes to a second configuration at the second temperature while dissipating the heat from the electrical component through a heat exchanger. After the heat is dissipated the shape memory alloy member is biased back to the first configuration by a bias member resulting in a reciprocal displacement of the shape memory alloy member.
In another method, an energy converter is connected to at least one shape memory alloy member wherein the energy converter produces a current in response to the movement of the shape memory alloy member. Next, the current is derived from at least one shape memory alloy member to an electrical storage.
In another method, a plurality of shape memory alloy members are thermally attached to a plate member. In this other method, the plate member is positioned between the electrical component and the heat exchanger wherein the bias member connects to the plate member. Then, the plurality of shape memory alloy members contract to the second configuration of the martensite state pulling the plate member toward the electrical component. The next step provides that the bias member then in turn biases the plate member along with the plurality of shape memory alloy members back to the first configuration.
The present invention has many advantages. These advantages relate to cooling an electrical component and generating energy from the heat emitted by the electrical component.
It is an advantage of the present invention to transfer heat from a component through a heat exchanger to a heat reservoir.
It is an advantage of the present invention to generate electricity from heat dissipated from a component without requiring additional energy.
It is still further an advantage of the present invention to provide a method of transferring heat from a component through a heat exchanger to a heat reservoir without requiring additional energy.
It is further an advantage of the present invention to provide a method of generating electricity from heat dissipated from a component without requiring additional energy.
These and other advantages and features of the invention are described in greater detail in the following detailed description of the presently preferred embodiments with reference to the accompanying drawings.